Memory processing in humans, monkeys, and pigeons will be studied in visual and auditory serial-probe-recognition tasks employing 5,000 different complex color pictures and 700 different natural sounds. The SPR task will allow fine-grained analysis to determine whether animals have the same, different, or simpler memory systems than humans through: transfer tests of conceptual development, maximum list length tests of memory span, probe delay tests of the serial-position function's primacy and recency effects, memory scanning tests of search stategies, interspecies tests of face memory, multidimensional scaling tests of animal and human categories. These investigations may have practical significance for improving memory by providing a foundation for neurophysiological and drug studies as well as scientific importance in discovering how cognition works in humans and animals.